Rubber track belts are used to propel agricultural work machines. Agricultural work machines which employ rubber track belts have several advantages over conventional agricultural work machines which employ wheels. The primary advantage of rubber track belts is that track belts distribute the weight of the work machine over a larger area than tires. Distributing the weight of the work machine over a larger area gives the work machine better floatation, or the ability to resist sinking into soft ground. In addition, as the rubber track belts move over the loose soil, the rubber track belts compact the soil much less as compared to wheels used on similarly sized agricultural work machines. Reducing the amount that the soil is compacted increases the yield of crops grown in the field as crops grow better in less compacted soil.
In addition, agricultural work machines which use rubber track belts have better traction than wheel type work machines. Since the size of the contact area between the rubber track belt and the ground is much larger than the size of the contact area between a wheel and the ground, a larger number of traction members, known as tread bars, are in contact with the ground at any given time. The larger number of tread bars allows more friction to be produced between the rubber track belt and the ground than between a tire and the ground. The greater amount of friction produces less slippage between the ground and the work machine thereby allowing more power to be applied to moving the work machine. This additional power allows greater loads to be pulled by a work machine that uses the rubber track belt than similar work machines that use wheels.
However, a problem with rubber track belts that have heretofore been used is that voids, or areas of low density material, are created under the belt as the belt advances through dirt, or other soft ground. In particular, as the track belt advances, the leading edge of the tread bars are pushed forward and down into the dirt. As the tread bar is moved forward and down, the tread bar compacts the dirt in front of the tread bar and creates a void in the dirt behind the trailing edge of the tread bar. This void does not have the density to support the weight of the work machine. Because the weight of the work machine is not supported by a portion of the track belt proximate to the void, the weight of the work machine is concentrated on the other portions of the rubber track belt in contact with dense soil. Concentrating the weight on a portion of the rubber track belt produces higher ground pressure and causes accelerated wear on the highly loaded portions of the rubber track belt.
Another problem with rubber track belts is wear caused when operating on roads or other hard surfaces. In particular, as the track belt advances around a drive wheel, the drive wheel applies a tension to the rubber track belt which stretches or elastically extends the rubber track belt. As the leading edge of the tread bars mounted on the rubber track belt disengage from the road, the tension in the rubber track belt pulls the trailing edge of the tread bar so as cause a scraping or scruffing action of the trailing edge of the tread bar along the surface of the road. This scruffing causes accelerated wear on the tread bar.
What is needed therefore is a rubber track belt which has improved traction and durability.